This invention relates to control systems for bathing systems such as portable spas.
A bathing system such as a spa typically includes a vessel for holding water, pumps, a blower, a light, a heater and a control for managing these features. The control usually includes a control panel and a series of switches which connect to the various components with electrical wire. Sensors then detect water temperature and water flow parameters, and feed this information into a microprocessor which operates the pumps and heater in accordance with programming. U.S. Pat. Nos. 5,361,215, 5,559,720 and 5,550,753 show various methods of implementing a microprocessor based spa control system.
For a properly designed system, the safety of the user and the equipment is important, and is typically concerned with the elimination of shock hazard through effective insulation and isolated circuity, which prevents normal supply voltage from reaching the user. Examples of isolation systems for spa side electronic control panels are described in U.S. Pat. Nos. 4,618,797 and 5,332,944.
The design of a system to control spas is complicated by the fact that there are electrical components in direct contact with the spa water. These electrical components, such as the heater, pumps, lights and blower are required to operate with precision and safety. If a malfunction occurs, it should be detected immediately and the spa shut down to protect the safety of the bather.
The accuracy of the temperature of the spa water is also important to the safety and comfort of the spa users. This temperature can vary depending on the number of bathers, the amount of insulation which is used in the construction of the spa, the operation of the pumps and blowers, and the outside temperature surrounding the spa.
When in continuous use, the spa temperature is controlled by temperature sensors which measure the temperature of the water, and selectively activate a pump to circulate water, and a heater which raises the water to the temperature set by the user at the control panel. There has not in the past been an effective method of accurately measuring and displaying the temperature of the spa if at least one of the various temperature sensors are not located at the spa, in direct contact with the water in the bathing vessel. The consequence of this is that the assembly of the control system into the spa is complicated and expensive, and requires special attention to the location, insulation and protection of the temperature sensors to achieve satisfactory results.
In normal service, a spa is kept continuously energized, and energy utilization is high during this time. However, bathers are typically in the spa water less than 5% of the daily time the spa is in place. At times when the spa is not in continuous use, the user may want to maintain a temperature close to use temperature, i.e. in an xe2x80x9calmost readyxe2x80x9d condition, so the spa may be quickly prepared for use by the bather. During this xe2x80x9calmost readyxe2x80x9d time, and while the owner is away from the spa site, e.g. on vacation, there is a need to maintain the water sanitation quality, and the temperature may be maintained at a lower level to conserve heat energy and therefore electrical energy. It would be advantageous if the spa computer system could record and predict the habits of the bather, and provide an optimum temperature maintenance based on the frequency of high and low usage. It would further be advantageous for the computer system to be able to predict the rate at which heat is lost and manage the pump and heater operations for optimum energy conservation, also reducing mechanical wear and tear on these components. These features are unknown and unavailable in known spa systems.
Because of the potentially corrosive nature of the spa water, and the possibility of the loss of the pump function due to pump failure, the system should have redundant systems to prevent damage to the heating element in the case of pump failure or water flow blockage. The use of mechanical devices such as pressure switches which respond to the pressure developed by pump outlet when the pump is activated, are prone to mechanical failure, corrosion failure and leaks. Flow switches which respond to the flow of water through a pipe or tube tend to be expensive, and subject to failure due to hair and foreign materials wrapping around the activating system, requiring frequent service. Pressure switches, currently the most popular method of water flow detection, can give false readings, are subject to damage and deterioration and often require calibration.
An additional hazard represented by the close proximity of electrical energy to the bathers, is a significant safety hazard to the user if the spa is not properly constructed and installed. The integrity of the ground earth system, which protects the spa user in case of an electrical failure of the heater element insulation system is important. Additionally, the control system preferably has an ability to detect and respond to a failure of the insulation system, and actively protect the user by disconnecting the device which has failed.
As systems controlled by microprocessors or other electronic controls can break down, be damaged by voltage surges, or fail through various component malfunctions, it would be highly desirable to have a redundant mechanism to protect from an overtemperature condition and shut down the system completely. This hardware high limit preferably would have the characteristic of tripping only once, and remaining in the off position, even after power down and repowering, but be resettable conveniently by the user without exposure to the high voltage wiring of the spa electrical system.
The control method of some conventional systems is subject to short cycling or rapid on-off pump activations because the location of the temperature sensors can cool off more quickly than the spa water.
Typical known spa control systems have employed a mechanical pressure switch or a mechanical flow switch which are subject to calibration failure, or mechanical breakdown. These random failures are difficult to repair, and present a considerable inconvenience to the user, since a spa is too large to move and must be repaired by a spa service technician.
Known spa control systems do not teach or use a method or technique of protecting the user from electric shock when the insulation of the electrical heater element is damaged and breached and the live electrical current is exposed to the bather""s water and the ground line is absent.
A ground fault circuit interrupter (GFCI) is employed in typical spa systems which is remotely mounted in the power supply line to the spa. This GFCI must be tested by the user before each use to insure that it is functional, presenting an inconvenience.
An aspect of this invention is a control board integrated ground fault circuit interrupter (GFCI) circuit which detects when there is a fault in the electrical insulation of controlled components and switches off all power to the components, if such fault results in an imbalance in the incoming power line.
Another aspect is a technique for testing and resetting the ground fault interrupter from the control panel of the bathing system.
A further aspect is a solid state ground fault circuit interrupter, integral with the control system, which is automatically tested and reset by the controller on regular intervals.
Another aspect is a technique for verifying the integrity of the ground hookup in the spa power line hookup by the computer, and disabling the spa control system if an adequate ground is not installed, meanwhile displaying an error message at the spa side control panel.
A further aspect is a technique for detecting a failure of a spa component which could cause hazard to a bather through electrification of the spa water and flow of electrical energy in the ground of the spa, and disabling the faulty component, and displaying in a warning message to the spa occupant at the spa side control panel.
Another aspect is the containment of all electrical contacts with the water within the shell of a grounded current collector, such as a heater element and temperature sensor.
Thus, according to an aspect of the invention, a control system for bathers is disclosed, including an enclosure, a control circuit assembly disposed within the enclosure, and an electrically powered circuit attached to the enclosure and including an electrical ground connected to earth ground. The control circuit assembly further including ground continuity detector apparatus for detecting continuity of the electrical ground and providing an electrical detector signal to the control circuit assembly indicative of a ground continuity status.
According to another aspect of the invention, a control system for bathers is described, which includes an enclosure, a control circuit assembly disposed within the enclosure, and a power supply connected to line voltage to energize the control circuit assembly. An electrically powered apparatus is controlled by the control circuit assembly, with at least one conductor connected from the electrically powered apparatus to earth ground. The control circuit assembly further includes a ground continuity detector circuit for detecting continuity of the conductor to ground and providing a detector signal to the control circuit assembly.
According to another aspect, a control system for a water spa is described, and includes a control circuit located in the vicinity of the spa, with a control panel connected to the control circuit. A high power supply is connected to the control circuit, the high power supply including at least two power supply conductors. The control circuit includes a plurality of high power outputs for connection to one or more spa devices powered by the high power supply, and sense circuitry for detecting a current imbalance in the high power conductors. A disconnection circuit apparatus is responsive to the sense circuitry for disconnection of the high power outputs from the respective spa devices when a current imbalance is detected, this disconnection of the high power outputs occurring without disconnecting power from the control circuit.